I think Aiden is saving up/having plans for a server, so this sort of was a test version. (None of his command blocks worked either! hahaha) I think it was the lag, with a combination of the combat update that did us in. Having a shield is useful in terms of negating skeletons, but not being able to go ham on zombies who still do some damage when they hit your shield is devastating in UHC! And then the lag comes in where you drop your shield to swing but you're 3 seconds behind and the zombie hits you, but if you don't try to attack it'll just keep attacking you for half a heart till you're dead...
N E WAYS
On the last PC server iteration we had a UHC map, I wonder why we couldn't set it up on that again? Most people have a decent connection to it.